Thirteen experiments are proposed to examine the production and comprehension of sentences by child and adult speakers of English, French, German, Hungarian, Italian, and Serbo-Croatian. The principle focus of the experiments is on the processing of devices involved with subjectivalization and reference-identification. The experiments seek to test the resilience of a plurifunctional, parallel-activation model of sentence processing called the "competition model." This model is presented as a performance model and not a competence model. As a model of adult processing, it seeks to account for performance in terms of relative cue weight. As a developmental model, it seeks to explain the order of acquisition of particular uses of grammatical devices in terms of the relative "cue validity" of those devices. The experiments include eight studies of sentence comprehension and five of sentence production. The studies of comprehension examine: 1) the impact of ungrammaticality on sentence interpretation, 2) the competition of case-marking with agreement marking in Serbo-Croatian and Hungarian, 3) the processing of multiple agreement cues in Hungarian, 4) the competition of clitic marking with agreement marking in French and Italian, 5) the processing of relative clauses in word-order varying languages, 6) late acquisitions of grammatical devices in English and Italian, 7) the interpretation of full and clitic pronouns in Italian, and 8) the acquisition of switch-reference marking in Hungarian. The studies of production examine: 1) on-going description of a film with a story-line, 2) use of lexical and syntactic primes and topical probes, 3) the impact of delay on retelling, and 4) developmental patterns in the control of discourse-based devices.